[SalesForce] Triggered Send Data Extension

There are 2 ways that we use to pass user information to Landing Pages:

Option 1: QueryParameter

In Email:

%%[VAR @email,@name,@landingpage
Set @email = 'email@example.com' 
Set @name = 'Test' 
Set @landingpage = Concat('https://pub.exacttarget.com/landingpage?email=',@email,'&name=',@name)
]%% 
<a href = "%%=RedirectTo(@landingpage)=%%">Click Here</a>

On LandingPage:

<form>
  Name:<br>
  <input type="text" name="name" value="%%=v(QueryParameter('name'))=%%"><br>
  Email:<br>
  <input type="text" name="email" value="%%=v(QueryParameter('email'))=%%">
</form>

Option 2: LookupRows & DataView

In Email:

%%[VAR @subscriberkey,@landingpage
Set @subscriberkey= '123456789' 
Set @landingpage = Concat('https://pub.exacttarget.com/landingpage?key=',@subscriberkey)
]%% 
<a href = "%%=RedirectTo(@landingpage)=%%">Click Here</a>

On LandingPage:

%%[
var @key, @email, @name
set @key = QueryParameter("key")
set @email = FIELD(ROW(LookupRows("_Subscribers","SubscriberKey",@key),1), "EmailAddress")
set @name = FIELD(ROW(LookupRows("Example_Customer_Data_DE","SubscriberKey",@key),1), "Name")
]%%
<form>
  Name:<br>
  <input type="text" name="name" value="%%=v(@name)=%%"><br>
  Email:<br>
  <input type="text" name="email" value="%%=v(@email)=%%">
</form>

Note that both of these methods are taking values from AMPScript at the time of send, and appending them to the destination URL string. For this reason, you may need some security/hashing/encoding to prevent malicious attempts to access your customer data via the form.

I hope that helps.

Triggered Send Data Extensions are meant to be a log of API calls, not a primary source for subscriber data -- which is why Email Address and Subscriber Key cannot be primary keys.

With no primary key, there's nothing stopping multiple emails being triggered for a single subscriber. So unless you've added some other primary key (not recommended) or are utilizing an Exclusion Script), there will be duplicates in your TSD DE.

I'd suggest a single master Data Extension and a set of Queries in an Automation to take rows from your Triggered Send Data Extensions and upsert them into your master.

Or, as you mentioned, just upsert rows in your Data Extension directly from your page.